According to traditional techniques, a vacuum treatment process for substrates was as follows:
Loading into the vacuum chamber one or more substrates that are to be treated under different conditions according to the requirements of the process.
On conclusion of the treatments, a successive cycle is initiated during which the vacuum chamber returned to atmospheric pressure, is opened.
Utilizing a fore-chamber of conventional type which, after its evacuation, allows insertion of the sample or samples into the vacuum chamber by mechanical movement.
During this old process, there were idle times during which the deposition operation was not working, or else it was necessary to use very expensive equipments.
Consequently, idle times and limited versatility, particularly during research phases and setting up of the processes were the most evident inconveniences encountered with the previous system. Besides it was not always possible, even at high cost, to retrofit a fore-chamber to an old plant.